Disk drives are often used to record data onto or to reproduce data from a recording media. A disk drive can include a rotating magnetic disk and a head actuated over the disk. Such actuation of the head typically occurs as part of a seek operation to magnetically write data to and read data from the disk. During the seek operation, an actuator pivots about an actuator pivot to move the head over the disk. The actuator pivot includes pivot ball bearings lubricated with grease to facilitate a smooth actuator movement during seek operations.
A disk of a disk drive includes a plurality of radially spaced, concentric tracks for recording user data. The storage device industry is continually striving to increase the recording density of the disk, or in other words, the amount of data that can be stored in a given area on the disk. One way of increasing the recording density of the disk is to increase the number of tracks per inch (TPI) on the disk.
In contemporary disk drives with a high number of TPI and fast seek completion times, grease buildup in the actuator pivot can occur due to prolonged, limited motion of the actuator. This prolonged limited motion can result from repeated accessing of data confined within a small area of the disk. Over time, such prolonged limited motion can lead to a redistribution of grease around the perimeter of the limited range of motion of the actuator.
In a mild case, the grease buildup can manifest as increased settle times, or in other words, the time needed for the head to reach its desired location on the disk. In a worse case, the grease buildup may lead to failure of the disk drive as the actuator cannot overcome the “grease bump” when the actuator needs to seek across a larger area of the disk. Consequently, failure to move the head onto a ramp for resting the heads during a power-down of the disk drive can cause the head to touch the disk, thereby creating a “head on media” (HoM) situation which can ultimately destroy the disk drive.